Diesel engines can be operated on a combination of diesel fuel and a coal-water slurry, using fuel injectors which inject both the diesel fuel and the slurry into the engine. For example, U.S. Pat. No. 4,736,712 describes a self purging dual fuel injector which first injects a pilot charge of diesel fuel into the engine, followed by coal slurry.
When an injector is used to release coal-water slurry fuel into a diesel engine, the slurry in the high pressure cavities of the injector can lose its fluidity due to a loss of water through the needle valve guide clearance, and the injector can easily become clogged with dried coal particles. Thus, there is a need for coal-water slurry fuel injectors which resist clogging.
Accordingly, one object of this invention it to provide new and improved fuel injectors for diesel engines.
Another object is to provide new and improved coal slurry fuel injectors which resist clogging.